Abstract: The spark plug includes a cylindrical insulator, a center electrode provided in the insulator, and a cylindrical metal shell provided around the insulator. A ledge portion of the metal shell has a frontward facing surface facing a front side, a rearward facing surface facing a rear side, and a connection surface connecting the rearward facing surface and the frontward facing surface. The rearward facing surface engages with a step portion of the insulator. The metal shell includes a front cylindrical portion connected to the front side of the ledge portion. The inner circumferential surface of the front cylindrical portion is connected to the frontward facing surface of the ledge portion via a chamfered surface or a rounded surface. A corner at which the connection surface and the frontward facing surface are connected is located on the front side with respect to a front end of the insulator.

Abstract: The spark plug includes a cylindrical insulator, a center electrode provided in the insulator, and a cylindrical metal shell provided around the insulator. A ledge portion of the metal shell has a frontward facing surface facing a front side, a rearward facing surface facing a rear side, and a connection surface connecting the rearward facing surface and the frontward facing surface. The rearward facing surface engages with a step portion of the insulator. The metal shell includes a front cylindrical portion connected to the front side of the ledge portion. The inner circumferential surface of the front cylindrical portion is connected to the frontward facing surface of the ledge portion via a chamfered surface or a rounded surface. A corner at which the connection surface and the frontward facing surface are connected is located on the front side with respect to a front end of the insulator.

Abstract: A spark plug that provides an increase in the combustion speed of an engine. The spark plug includes a center electrode, a ground electrode, an insulator, and a cover portion. In a cross-sectional area of a region surrounded by an inner wall surface of the cover portion in a cross section taken along a plane perpendicular to an axial line CX of the spark plug, the cover portion includes: a narrow portion positioned on the front end side with respect to the ground electrode in the direction of the axial line CX and narrowed such that the cross-sectional area is smallest; and a cover front portion positioned on the front end side of the narrow portion and having the cross-sectional area that is larger than the cross-sectional area of the narrow portion and that is largest at the front end of the cover front portion.

Abstract: A pressure sensor includes: a diaphragm joined to a front side of a housing via a joint portion; a sensor portion; a connection portion connecting the diaphragm to the sensor portion; and a heat receiving portion disposed at the front side of the diaphragm. When: a minimum value of an area of a minimum inclusion region which is a virtual region, which include a cross-section of a portion from the heat receiving portion to the diaphragm and of which an overall length of a contour become minimum on a cross-section perpendicular to the axial line, is defined as a connection area Sn; and an area of a region surrounded by the joint portion on a projection plane perpendicular to the axial line when the diaphragm and the heat receiving portion are projected onto the projection plane is defined as a diaphragm effective area Sd, (Sn/Sd)?0.25 is satisfied.

Abstract: A fuel gas supply path in a fuel cell stack includes in series a first path, a second path, and a third path. In the second path, two inlets of the fuel gas in each of power generating cells included in the second path are located at a first position PA and a second position PB, and the position of one outlet of the fuel gas in each power generating cell is located at a third position PC. In the third path, an inlet of the fuel gas in each of power generating cells included in the third path is located at a position coinciding with the third position PC when the power generating cells are viewed in the stacking direction, and an outlet of the fuel gas in each power generating cell is located at a position between the first position PA and the second position PB.

Abstract: The fuel cell includes a fuel cell stack in which a plurality of planar power generation cells are stacked in a thickness direction thereof. The fuel cell also includes a heat exchanger provided between the two adjacent power generation cells in the stacking direction and in contact with the power generation cells, and including an internal first flow path that passes the oxidant gas or fuel gas supplied from outside. The fuel cell also includes a second flow path connected to an outlet side of the first flow path of the heat exchanger and to the cathode side or the anode side of each of the power generation cells, and supplying the oxidant gas or fuel gas that has passed through the first flow path to the cathode side or anode side of each of the power generation cells on both sides in the stacking direction of the heat exchanger.

Abstract: A pressure sensor includes: a diaphragm joined to a front side of a housing via a joint portion; a sensor portion; a connection portion connecting the diaphragm to the sensor portion; and a heat receiving portion disposed at the front side of the diaphragm. When: a minimum value of an area of a minimum inclusion region which is a virtual region, which include a cross-section of a portion from the heat receiving portion to the diaphragm and of which an overall length of a contour become minimum on a cross-section perpendicular to the axial line, is defined as a connection area Sn; and an area of a region surrounded by the joint portion on a projection plane perpendicular to the axial line when the diaphragm and the heat receiving portion are projected onto the projection plane is defined as a diaphragm effective area Sd, (Sn/Sd)?0.25 is satisfied.

Abstract: A fuel cell stack (1) includes a plurality of stacked power generation cells (3), a heat exchange unit (7) provided between adjacent two of the power generation cells, a fuel gas supply path arranged to supply the power generation cells with a fuel gas, and an oxidant gas supply path (3, 7, 33, 34, 38) arranged to supply the power generation cells with an oxidant gas, wherein the fuel gas supply path includes in series a first path (7, 31) passing through the heat exchange unit (7), a second path (3, 32, 35, 37) passing through some of the plurality of power generation cells (3) in parallel, and a third path (3, 32, 36) passing through the other power generation cells in parallel.

Abstract: A fuel gas supply path in a fuel cell stack includes in series a first path, a second path, and a third path. In the second path, two inlets of the fuel gas in each of power generating cells included in the second path are located at a first position PA and a second position PB, and the position of one outlet of the fuel gas in each power generating cell is located at a third position PC. In the third path, an inlet of the fuel gas in each of power generating cells included in the third path is located at a position coinciding with the third position PC when the power generating cells are viewed in the stacking direction, and an outlet of the fuel gas in each power generating cell is located at a position between the first position PA and the second position PB.

Abstract: The fuel cell includes a fuel cell stack in which a plurality of planar power generation cells are stacked in a thickness direction thereof. The fuel cell also includes a heat exchanger provided between the two adjacent power generation cells in the stacking direction and in contact with the power generation cells, and including an internal first flow path that passes the oxidant gas or fuel gas supplied from outside. The fuel cell also includes a second flow path connected to an outlet side of the first flow path of the heat exchanger and to the cathode side or the anode side of each of the power generation cells, and supplying the oxidant gas or fuel gas that has passed through the first flow path to the cathode side or anode side of each of the power generation cells on both sides in the stacking direction of the heat exchanger.

Abstract: A fuel cell stack (1) includes a plurality of stacked power generation cells (3), a heat exchange unit (7) provided between adjacent two of the power generation cells, a fuel gas supply path arranged to supply the power generation cells with a fuel gas, and an oxidant gas supply path (3, 7, 33, 34, 38) arranged to supply the power generation cells with an oxidant gas, wherein the fuel gas supply path includes in series a first path (7, 31) passing through the heat exchange unit (7), a second path (3, 32, 35, 37) passing through some of the plurality of power generation cells (3) in parallel, and a third path (3, 32, 36) passing through the other power generation cells in parallel.